bi-wire speaker cables with single wire spkeakers

I have a pair of Cardas Cross bi-wire (internal) speaker cables. If I get new speakers that do not have provisions for bi-wiring what is the best way to connect the 2 spades on each cable to a single binding post on the speaker?
You can reterminate the cables at the speaker end, using new spades and joining the conductors at the spade. That would effectively convert your biwire cables to single-wire ones.

If you don't want to do the retermination, you can just connect two spades to a single binding post and tighten down very well. The risk is that the connection will loosen, so check it regularly. You can use one of Herbie's Binding Post Washers to help keep it snug. A shot of DeOxit Gold wouldn't hurt, and/or a silver paste like Mapleshade Silclear, to help secure the electrical connection.

Herbie's washers
Don't know how Cardas terminates their cables but one of the nice features of my MIT cables is that you can just swap out the termination such that you have one pair spades and the other banana so they both fit nice and snug in a single set of binding posts.
be very careful if you "stack" the two spades onto one binding post. Cardas spades are pretty hefty and you will probably have to rotate one with respect to the other to get a connection. If you do that, make VERY SURE that the spades from one leg (+ or -) do not touch the other leg and that they are very snug so that they cannot shift. It would be very easy to short the outputs, in which case, if you are lucky, you will need to replace fuses; if unlucky, lots more. If I were doing that I would use electrical tape or some other insulator between the two legs.
I do the same and as mentioned stack both spades into the single post. To address the issue of them coming apart I tighten the post and stick an expired credit card or gift card in-between the Postive and Negative posts.
Great idea, Justlisten. After tonight at the mall, I might have to superglue my current card there ;~)
I guess I've been living dangerously for a long time now. I also stack my bi-wire cables but am careful not to move my speakers at all, never walk near my cables (they're not in a traffic flow area), and I'm sure to really tighten my binding posts well. My binding posts look like a rat's nest compared to most as my speakers ARE bi-wire designed but after experimenting, just for fun, with doubling up the runs onto each terminal and trying another pair of cables in addition (not the same brand but I ran them on my bass terminals), I heard a definite improvement in both top and bottom. With that in mind, I bought another identical pair of my original cables (Harmonic Tech Pro-9's) also/purposely bi-wired (to be "future proof" in flexibility) and now I'm running a total of 8 spades to 4 binding posts... no, make that 10 spades because I've had my Walker High Definition Links to my mid/tweeter terminals since day 1 also, so these binding posts are actually holding 3 reasonably thick spades stacked up, per post. Besides the obvious "major event" status when I do my connection cleaning ( I Like Caig's De-oxit), this set-up has yielded the best sound for me... adding the second pair of identical cables sort of synergized the whole scenario, if you will. That is a great idea though, Justlisten, but did you say "Used" credit cards? or cards you wanted to keep from using anymore? Just be careful back there... Happy Lissn'n.